Gearless differential



Feb. 20, 1923. 1,446,325

4 J. D. ALLEN GEARLESS DIFFERENTIALZ Original Filed Jan; 30, 1919 5 sheets-sheet l ATTORNEY.

%%, g'y INVENTOR.

Feb. 20?, 11923. 1,446,325

J. D. ALLEN v GEARLESS DIFFERENTIAL Original Filed Jan. V50, 1919 5 sheets-sheet 2 I r I J. DHALLEN GEARLESS DIFFERENTIAL Original Filed Jan. 50, 1919 3 sheets-sheet 5 UNVENTOR.

" ATTORNEY Patented Feb. 20, 1923.

Milli ll) STATES are JOHN D. ALLEN, or PI-iILADELZPI-IIA, PENNSYLVANIA.

GEARLESS DIFFERENTIAL.

Continuation of application Serial No.

1920'. set-m1 No. 400,111.

To all whom may concern Be it known that I, .lorrx 1); Annex, a

citizenoi"the United States, residing; at,

Philadelphia, in the county: oi Philadel- 5 phia and Stateof Pennsylvania, have invente'd new and'useiul improvements in Gearless Differentials, of w ich tlie'tollow intg is a specification. I

This application is filed to take the place o l" my application 'Ser. No. 2741309, tiled Jan. Ill), 1919 and ailoi'ved Feb. 26,1920, which, in turn, was a cor-tini'iation oi" my application Serfllio. lSttllST, tiled Aug. 18, 191"? and 'allbwGd'AugiS. 1918.

The present invention a dcvclo nnent oi the mechanisms covered by my Patents ii Nos, 1,238,730 of Sept. i. 1.)17; inst, of April 30,1918, 1,265,160 oi May 1918, anddfillilfitll'ot Dec. 2. 1919. its "object 20 and function are the same as those of said patented mechanisms, but it accomplishes the result 'by'improved means:

The invention may he termed, and is known as, a gearless (litterential. to distinguish it from the gear diltercntial'in coin- 111011"11SL, oi which it is designed to take the place). Strict-1vspeaking, however, the

name differential is a misnomer when ap plied to the hereinafter "described mechaof one driven shaft to vary automatically with respect to the speed of the other driven shaft. In my said prior patents and applications, I have used theterni compensating mechanism, but that is no more Strictly accurate than the term 5 differential. lFlowever. since it takes the 'ilacc, and perknown as the dill'erential, it will be known 40 as a differential andfto distinguish itironi the usual form, as a "grearl'es's (littercntial. I The distinguishing difference hetwcenthe usual gear differential and my gearlessditferential resides inthc fact that in mine the drive of the't'wo wheel shafts is quite independent, while in the former the drive oi ono wheel 'shait dependsiipoh the drive of the other.

lVith' the gear ditferentia when one wheel'losesitstractiom'that is to say, does not contactfivitln the ground or only contacts therewith with insuiiicient 'l'rictioirto caus'ethe wheel to roll "forward when the power is applied, the gear in the differential casing.

274,009, filed January so, 1919.. This applicationfiled "Juli 30,

attached to the other wheel shaft stands still, the driving casing, carrying the satellite pinions, revolves, andthe pinions rotate on their axes, running over the stationary gear and drivingth'e wheel which has lost its traction at twice the'sped of the" The result is that that wheel spins and the'otlier is powerless to move the vehicle. 'In other words, with the gear difi'erential, both" wheels must have traction before the vehicle can be propelled. While the condition I have described, of; one wl ieel entirely losing its traction and the vehicle consequently becoming stalled, only occurs in practice when one wheel gets into a mudhole or the like, it is evident that the con dition must frequentlyocciir in a small degree, as, for example, in traveling at more or less high speed over somewhat] rough roads, when one wheel or the other will con lie propelling" power is still divided be-[ tween the two wheels'proba'hly the outer wheel takes slightly more than hali'hut the outer wheel must turn taster than the casing of the (differential, the increment o't its speed varyinginversely' as the radiusoi the curve. The effect is that'thereis a (-,'0n-' 9o stant tendency oi the vehicle to sharpen the curve,- that is, to reduce the radius of its curvature, which is a source oi danger which the driver must counteract by the steering The principal'dang'er of the gear differ; ential, however, occurs when the vehicleis coasting or running by momentum, so that pinions.

the "gears on the wheel shafts become the drivers of the casing through: the satellite Under such conditions, assoon as one wheel runs faster than the other, the pinions are turned on their axes and react on thegeanot the other wheel sha-it' to tend to turn it hackwardly.

lt'now the last 1w to result in a considerable savin in power (gasolene) and increase in the life of the tires, in addition to preventing delays on account of the vehicle getting into a mud hole or the like, and reducing the danger of skidding and overturning. v

The essence of my invention consists in the means whereby each wheel shaft is driven quite independently of the other, yet either wheel is free to turn faster than the other, as when rounding a curve. Th se conditions hold true for backward drive as well as for forward. In rounding a curve the inner wheel does all the work of propelling the vehicle, the outer wheelrunning free until its speed becomes equal to that of the inner wheel again. If one wheel loses its traction, the other is available to drive the vehicle. The mechanism is so designed as to be of ample strength to take care of the heaviest truck loaded to its ultimate ca pacity. There is no lnternal friction in the mechanism, as there is in the gear differential, and there is no shock felt, or click heard, when the drive shifts from forward to reverse, as when the motor is throttled and the vehicle runs by momentum. These and other advantages are obtained by the construction and combination which will now be described in detail, in connection with the accompanying drawings, in which:

Fig. 1 is a longitudinal central section through the differentialmechanism; I v

Fig. 2 is a cross section through the same, on line 22 Fig. 1; a

Figs. 3 too are detail views of the parts. The driving casing 10, made in two parts as usual, comprises the hubs 11, adapted. to be journalled in bearings carried by the differential housing of the rear axle, and flanges 12, between or to whichthe driving or ring gear, not shown, is bolted. It is immaterial, as far as this invention is concerned, how the power from the motor. power shaft is transmitter to the casing. This casing is slotted or recessed in its periphery at two pairs of diametrically opposite points. 14, 1,4, and 15, 15, for a purpose which will hereinafter be explainedp Two driven members 16, 16, are turnably fitted within the casing and each comprises a web 17 an inwardly extending peripheral flange 18, within which are cut the rounded ratchet teeth 19, a short external rub 20,- fitting a recess in the casing, and a longer parent later on.

internal hub 21, the hubs being internally splined, as at 22, for engagei'nent with the ends of the wheel shafts, not shown. A washer or ring 23 is preferably placed between the adjacent inner ends of the driven member hubs, as shown.

On the hub members 21 is mounted the hub 24 of anintermediate member 25, which Tterm the spider, and comprising, in addi tion to said hub, the Web 26 and the diametrically opposite lugs 27, 27, which engage in the slots or recesses 14:, ll, in the casing. There isa small amount of play or lost motion between said lugs and slots, as shown in Fig. 2, the function of which will be ap- This spider is recessed on. both sides at diametrically opposite places, as shown at 28, the ends of each recess being rounded to constitute a seat 29 for the pawl 80, the two pawls in each recess facing in opposite directions. There are therefore four pawls on each side'of the spider, two for forward drive and two for reverse drive. Each pawl has a short trunnion 31, seated in a hole in the spider, and is normally pressed into engagement with the ratchet teeth 19 by a coil spring 32, seatedv in abore in the pawl and maintained in position therein by a headed pin The outer end 84 of the spring lies in a groove 35 in the spider, and the inner end 36 fits in a hole 37 in the pawl. Cap plates 38, screwed to the sides of the spider, hold the pawls and springs in place.

There remains to be described the means by which the pawls are disengaged from the ratchet teeth when the drive changes from forward to reverse, which means constitute the essential feature of the present invention. It consists in cams 40, 10, pivotally mounted on the spider, as by the pins all, 1-1, having lugs 4-2, snugly engaging in the slots or recesses 15 in the casing, and having noses e3, 43, which engage the pawls to force them inwardly out of engagement with the ratchet teeth. As shown, each cam consists of two duplicate parts carried by the pin 4l-1,'one

on each side of the web 26 of the spider, each of said parts being arrangedto engage alternately two pawls, one facing each Way. Each cam can be made in one-piece, if desired, and may act directly on the nose of the pawls, as shown in the drawing of my application aforesaid, Ser. No. 274,009, but I find that the action is improved by having thenoses of the cams act upon shoulders 44 formed on the sides of the pawls. The cams now have more of a rolling action on said shoulders than a direct push, which tends to eliminate any danger of the pawls stickmg.

the lugs 27 of the spider are shown as centrally located in the slots 14: in the casing. Now, whichever way the casing is turned, it

In Fig. 2, both forward and reverse pawls are shown in the neutral position and.

will move relatively to the spider until one or the other end otvsaid slots engage said lugs, which movement, from neutral ,position', does not amount ,to ,morethan three thirty-secondths otean =inchi Such relative movement-t the, casingon the spider must rock thecams on their pi.vots,since,the lugs 42 have no lostinotionin the slots in the casing The rocking-otthe ca1ns,rone way or the other, presses the pawls facing one way out of the path ot the ratchet teethand allows the pawlsvtacing the other way to move, under theinfluence of their springs, into engagement with said liQ6l1l1,LSOitll&t all the pawls tacingone way are in engagement with the teeth of the drivcnmembers by the time the ends of the slots 14 comeainto driving engagement with the lugs 27 of the spider. The teeth 19 and the spaces between themare so shaped that,i1": the pawls are not fully seated at the monienttthe spidercommences to .drive, they willvslip into full en gagement automatically. The parts are so proportioned and arranged that the. disenged pawls are always in proper position to come into engagement with the teeth as soon as permittedto do so-by the cams.

It will re: lilyvbe understood thatamechanismof this kind must be of great strength to withstand the tremendous forces transmitted through it, and inustbe absolutely certain in its operation, as-wel-l a's practically immune from wear. The mechanismabove described possesses all these 'attributesto a marked degree and has proved eminently satisfactory under vcrytrying conditions of use. The mode of assembling and fitting the driven members within the hubs ot the casing and spider makes it impossible for any displacementof said parts to occur. It will be seen that the parts wl1ich-take the load do so under compression so that there isno possibility of their breaking, whilethe only surfaces subjected to any appreciable wear are the tops of theyteeth andthe noses of the pawls, when the former overrun the latter owing to the outer wheel on a curve traveling faster than the inner wheel and driving casing. p

The mode ofoperation of the mechanism has been suliiciently described above. Either driven member isvtree to overrun the pawls whenever the wheel connectechto it has to cover more ground in a given time than the wheel on the other side of the vehicle, "If one wheel loses its traction, 'thepower is transmitted through theotherwheel, and the same is true it one wheel is turning taster than the other, as in rounding a curve. \Vhenthe vehicle runs byinomentn1n,.the pawls are changed and the driven members become the drivers, through the reverse pawls. of the casing, ring gear and motor, if the clutch isvleft in. 'It is an utter impossibility "for one wheel to turn backwardly while thevehicle is moving forwardly, as

suit in a very markedfsaving in fuel and wear of tires, as well as giving the driver more complete and safe control'ot his vchicle.

,I'Iaving thus described my'invention and its mode of operation, what I claim as new is 1. In a inechanism of the class described, the combination of a driving casing having slots in its periphery and provided with hubsadapted to be journalled viniiixed bearings; a spider within said casing having lugs loosely fitting certain of said slots and provided with a hub; two driven inembers, each having a set of ratchet teeth, and'a hub journalled in theesaid hubs ot the casing and ot the spider; oppositely tacingpawls carried by said spider to engage said teeth; and pawl actuators pivotally carried by the spider and havinglugs snugly fitting others of said slots.

2. In a mechanism of the class described, the combination of a driving casinghaving slots in its periphery, an intermediate driving spider locatedcentrally in said casing and having diametrically opposite lugs loosely litting'two of said slots, two independent driven members locatedwithin said casingone on each side ofsaid spider and each comprising-an internal ratchet wheel, pairs of oppositely tacingpawls seated on opposite sides of said spider, springs tending to holdsaid'pawls in engagement with said ratchet'wheels, andcams pivoted on said spider in position to engage eitherone of e a pair ol oppositely facing pawls to disengage it from ratchet wheel, each cam having a lug engaging another of said slots in the casing,

' 3. In a mechanism of the class described, the combination with a hollow driving memher; an intermediate'member therein having a positive but lost motion connection with saidedriving member and two independent driven members each provided with ratchetteeth ot'means tor operatively connecting said intermediate-member to one of said driven-members for rotation in one direction, and otherdneans tor o1i eratively by said intermediate member and controlled by .the position of the latter relatively to said driving 1Yl111l -l',t0 disengage the connecting means operative for rotation in one direction while permitting that operative in the other direction to remain connected.

4. In a mechanism of the class described, the combination of anouter driving member provided with power connections; an intermediate driving member capable of a limited turning movement in said outer member; two driven members, one on each side of said intermediate member; pawl and ratchet connections between said intermediate and driven members for driving the latter in either direction; and cams, can ried by said intermediate member for engaging said pawls and provided with parts engaged by said outer driving member, whereby the pawls for driving in one or the other direction are always disengaged, depending upon the relative position of the outer and intermediate members.

5. In a. mechanism of the class described,

the combination of a driving casing; a

spider within the same and capable of only a limitedrotary movement relatively thereto; a driven member on each side of said spider and provided with internal ratchet teeth; oppositely facing pawls carried by said spider in position to engage said teeth; springs tending to hold said pawls in engagement; and means, independent of the pawls, carried by the spider and engaged by the casing, and actuated by the relative rotation of the casing and spider, to disengage the pawls facing one way while permitting those facing the other way to en gage said teeth.

6. In a mechanism of theclass described, the combination of a driving member, composed of a hollow casing carrying a gear, and a central spider having a positive connection with said casing but capable of a slight turning movement therewithin; a

driven member on each side of said spider and provided with a toothed annulus; two pairs of oppositely facing pawls carried by i said spider in position to engage each annulus; cams carried by said spider in position to engage one of each pair of pawls at a time, and means on said cams and in en gagement with. said casing, whereby said cams are actuated, when relative movement occurs between the casing and spider, to disengage the pawls facing one way.

7. In a mechanism of the class described, the combination of a twopart driving memher, the parts of which can turn slightly relatively to each other; two driven members therein having means to non-rotatively connect them to the shafts to be driven and each comprising an internal ratchet wheel; pawls carried by one of said parts; springs holding said pawls in engagement with said ratchet wheels; and cams, carried by the same part the pawls-but in engagement with the other part, for disengaging one half of the pawls at a time according to the relative position of the two parts of the driving member.

8. In a mechanism of the class described,

the combination of a member constructed to be operated by power and constituting a hollow casing adapted to be journalled in bearings; a spider within said casing and havinga lost motion driving connection said casing,whereby they are rocked when-- ever a relative angular movement takes place between the casing and spider, each cam alternatively engaging one or the other of a pair of oppositely facing pawls to disengage it from the adjacent ratchetwheel.

9. In a mechanism of the class described, the combination with the drivingicasing, the intermediate member having a limited rotary movement relative to the casing, and the driven members each comprising an internal ratchet wheel, of pawls carried by the intermediate member and spring pressed into engagement with said ratchet wheels, each pawl'having a. lateralshoulder, and cams pivoted on said intermediate member and having parts engaged by said driving casing, whereby they are rocked on their pivots when relative rotary movement takes place between, the casing and the intermediate member, each cam engaging alternatively the shoulder on one of a pair of said pawls to disengage it from its ratchet wheel, the pawls of each pair facing inopposite directions.

10. In a mechanism of the class described, the combination with a driven member h av ing internal ratchet teeth and a driving member carrying spring pressed pawls to engage said teeth, each pawl having a shoulder formed on one side, of cams carried by said driving member in position to act on said shoulders-to disengage said pawls.

11. In a mechanism of the of the class described, the combination with a driven member having internal ratchet teeth, of a driving member comprising an inner and an outer part capable of alimited relative angular movement, spring pressed pawls carried by said inner part in position to engage said teeth, a shoulder on the side of each pawl, and cams carried by said inner part and actuated by the angular movement of the same within said outer part, said cams acting upon said shoulders with a rolling action todisengage said pawls, one half of the pawls being arranged to drive in one direction and the other half in the other direction, and the cams, when in one position, disengaging one half of the pawls while permitting the other half to remain in engagement.

12. A gearless differential mechanism, comprising in combination with the driving member and thetwo driven members, of an intermediate member driven by said driving member but capable of a slight rotative II'IOVGHIGIlt relatively thereto, and means to connect said intermediate member to said driven members to drive them in either direction, said means comprising internal ratchet teeth on said driven members and spring pressed pawls on said intermediate member, half of the pawls facing one way and the other half the other way, and means to hold half of the pawls disengaged at any given time, said means comprising cams carried by said intermediate member and operatively engaged by said driving member, said cams being operated to release one half the pawls and disengage the other half whenever relative rotative movement takes place between the driving member and the intermediate member.

13. A gearless diiferential mechanism,

comprising a driving casing, two driven members therein, a spider intermediate said casing and driven members, said spider having a lost motion engagement with said casing, oppositely facing means carried by the spider to connect it to the driven members for drive in either direction, and independent means carried by the spider and having operative engagement with the casing, for permitting only the'connecting means facing one way to be operative at any one time.

14. A gearless differential mechanism, comprising a hollow driving casing, two alined driven members therein and each provided with ratchet teeth, a spider centrally located within said casing between said driven members, said spider having a positive lost motion driving connection with said casing, oppositely facing independent pawls pivoted on each side of said spider and spring pressed into engagement with the adjacent ratchet teeth, and separate means, carried by said spider and engaged by said casing, to alternately disengage the oppositely facing pawls.

In testimony whereof I have hereunto set my hand.

JOHN D. ALLEN. 

